案例说明：
在生产环境需要将集群中架构转换为单实例环境，本案例以备库转换为单实例库为案例，介绍了两种方案，一种在数据库数据量小的环境下采用 sys_dumpall 导出导入方式建立单实例库；另外一种是在数据量大的情况下，采用物理copy的方式建立单实例库。
案例数据库版本:
PROD=# select version();
VERSION ------------------------------------------------------------------------------------------------------------------
Kingbase V008R003C002B0270 on x86_64-unknown-linux-gnu, compiled by gcc (GCC) 4.1.2 20080704 (Red Hat 4.1.2-46), 64-bit
(1 row)
案例架构：
查看集群状态：
1、集群节点状态
[kingbase@node1 bin]$ ./ksql -U SYSTEM -W 123456 TEST -h 192.168.7.243 -p 9999
ksql (V008R003C002B0270)
Type "help" for help.
TEST=# show pool_nodes;
node_id | hostname | port | status | lb_weight | role | select_cnt | load_balance_node | replication_del
ay
---------+---------------+-------+--------+-----------+---------+------------+-------------------+----------------
---
0 | 192.168.7.243 | 54321 | up | 0.500000 | primary | 0 | false | 0
1 | 192.168.7.248 | 54321 | up | 0.500000 | standby | 0 | true | 0
(2 rows)
2）流复制状态
[kingbase@node3 bin]$ ./ksql -U SYSTEM -W 123456 TEST
ksql (V008R003C002B0270)
Type "help" for help.
TEST=# select * from sys_stat_replication;
PID | USESYSID | USENAME | APPLICATION_NAME | CLIENT_ADDR | CLIENT_HOSTNAME | CLIENT_PORT | BACKEND_ST
ART | BACKEND_XMIN | STATE | SENT_LOCATION | WRITE_LOCATION | FLUSH_LOCATION | REPLAY_LOCATION | SYNC_
PRIORITY | SYNC_STATE
------+----------+---------+------------------+---------------+-----------------+-------------+-------------------
3393 | 10 | SYSTEM | node2 | 192.168.7.248 | | 9968 | 2021-03-01 12:09:1
2.662830+08 | | streaming | 0/B0CC040 | 0/B0CC040 | 0/B0CC040 | 0/B0CC040 | 2 | sync
(1 row)
案例一： sys_dumpall导出导入方式（用于数据量小的架构，在生产环境下，不能保证单实例库的数据和集群中的数据是一致的）。
1、集群测试数据
PROD=# create table t1 (id int ,name varchar(10));
CREATE TABLE
PROD=# insert into t1 values(generate_series(1,10000),'usr'||generate_series(1,10000));
INSERT 0 10000
PROD=# select count(*) from t1;
COUNT
-------
10000
(1 row)
2、在备库主机创建新的实例
# 创建单实例库数据目录
[kingbase@node1 bin]$ mkdir -p /data/kingbase/v8r3c/data
# 初始化单实例库
[kingbase@node1 bin]$ pwd
/home/kingbase/cluster/ha/db/bin
[kingbase@node1 bin]$ ./initdb -U system -W 123456 -E utf8 --case-insensitive -D /data/kingbase/v8r3c/data
.....
Success. You can now start the database server using:
./sys_ctl -D /data/kingbase/v8r3c/data -l logfile start
3、从备库备份数据（sys_dumpall）
[kingbase@node1 bin]$ ./sys_dumpall -U SYSTEM -W 123456 > ~/db.sql
sys_dumpall: role name starting with "sys_" skipped (SYSSAO)
sys_dumpall: role name starting with "sys_" skipped (SYSSSO)
sys_dumpall: role name starting with "sys_" skipped (SYSTEM)
4、启动单实例数据库并导入数据
# 启动数据库服务
[kingbase@node1 bin]$ ./sys_ctl start -D /data/kingbase/v8r3c/data/
server starting
[kingbase@node1 bin]$ LOG: redirecting log output to logging collector process
HINT: Future log output will appear in directory "sys_log".
[kingbase@node1 bin]$ netstat -an |grep 54323
tcp 0 0 0.0.0.0:54323 0.0.0.0:* LISTEN
tcp6 0 0 :::54323 :::* LISTEN
unix 2 [ ACC ] STREAM LISTENING 42092 /tmp/.s.KINGBASE.54323
You have mail in /var/spool/mail/kingbase
# 连接数据库并导入数据
[kingbase@node1 bin]$ ./ksql -U system -W 123456 test -p 54323
ksql (V008R003C002B0270)
Type "help" for help.
test=# \l
List of databases
Name | Owner | Encoding | Collate | Ctype | Access privileges
-----------+--------+----------+-------------+-------------+--------------------
SAMPLES | system | UTF8 | en_US.UTF-8 | en_US.UTF-8 |
SECURITY | system | UTF8 | en_US.UTF-8 | en_US.UTF-8 |
TEMPLATE0 | system | UTF8 | en_US.UTF-8 | en_US.UTF-8 | =c/system +
| | | | | system=CTcb/system
TEMPLATE1 | system | UTF8 | en_US.UTF-8 | en_US.UTF-8 | =c/system +
| | | | | system=CTcb/system
TEMPLATE2 | system | UTF8 | en_US.UTF-8 | en_US.UTF-8 | =Tc/system +
| | | | | system=CTcb/system
TEST | system | UTF8 | en_US.UTF-8 | en_US.UTF-8 |
(6 rows)
# 导入备库备份数据
test=# \i /home/kingbase/db.sql
SET
SET
SET
CREATE DATABASE
ksql:/home/kingbase/db.sql:25: ERROR: database "SECURITY" already exists
REVOKE
GRANT
You are now connected to database "PROD" as user "system".
SET
SET
SET
SET
SET
SET
set_config
-----------------
"$USER", PUBLIC
(1 row)
.......
5、查看单实例库数据
TEST=# \l
List of databases
Name | Owner | Encoding | Collate | Ctype | Access privileges
-----------+--------+----------+-------------+-------------+--------------------
PROD | system | UTF8 | en_US.UTF-8 | en_US.UTF-8 |
SAMPLES | system | UTF8 | en_US.UTF-8 | en_US.UTF-8 |
SECURITY | system | UTF8 | en_US.UTF-8 | en_US.UTF-8 |
TEMPLATE0 | system | UTF8 | en_US.UTF-8 | en_US.UTF-8 | =c/system +
| | | | | system=CTcb/system
TEMPLATE1 | system | UTF8 | en_US.UTF-8 | en_US.UTF-8 | system=CTcb/system+
| | | | | =c/system
TEMPLATE2 | system | UTF8 | en_US.UTF-8 | en_US.UTF-8 | =Tc/system +
| | | | | system=CTcb/system
TEST | system | UTF8 | en_US.UTF-8 | en_US.UTF-8 |
(7 rows)
TEST=# \c PROD
You are now connected to database "PROD" as user "system".
PROD=# \d
List of relations
Schema | Name | Type | Owner
--------+-------------------------------+-------+--------
PUBLIC | pathman_cache_stats | view | system
PUBLIC | pathman_concurrent_part_tasks | view | system
PUBLIC | pathman_config | table | system
PUBLIC | pathman_config_params | table | system
PUBLIC | pathman_partition_list | view | system
PUBLIC | T1 | table | system
(6 rows)
PROD=# select count(*) from t1;
count
-------
10000
(1 row)
=== 从以上可以获知，集群中的数据已经导入到单实例库中，此时可以停止备库或删除集群===
案例2：物理拷贝方式（如果单实例库数据需要和集群数据一致，需要停止整个集群；如果不需要一致，只需要停止备库数据库服务即可）。
1、集群测试数据
PROD=# \d
List of relations
Schema | Name | Type | Owner
--------+-------------------------------+-------+--------
PUBLIC | PATHMAN_CACHE_STATS | view | SYSTEM
PUBLIC | PATHMAN_CONCURRENT_PART_TASKS | view | SYSTEM
PUBLIC | PATHMAN_CONFIG | table | SYSTEM
PUBLIC | PATHMAN_CONFIG_PARAMS | table | SYSTEM
PUBLIC | PATHMAN_PARTITION_LIST | view | SYSTEM
PUBLIC | T1 | table | SYSTEM
PUBLIC | T2 | table | SYSTEM
PUBLIC | T3 | table | SYSTEM
(8 rows)
PROD=# select count(*) from t1;
COUNT
-------
10000
(1 row)
.......
2、备库生成检查点
PROD=# checkpoint;
CHECKPOINT
3、停止备库cron任务和数据库服务
[root@node1 ~]# cat /etc/cron.d/KINGBASECRON
.......
#*/1 * * * * root /home/kingbase/cluster/ha/db/bin/network_rewind.sh
#*/1 * * * * root /home/kingbase/cluster/ha/kingbasecluster/bin/restartcluster.sh
# 停止备库数据库服务
[kingbase@node1 bin]$ ./sys_ctl stop -D ../data
waiting for server to shut down.... done
server stopped
4、建立单实例库
# 创建单实例库数据目录
[kingbase@node1 bin]$ mkdir -p /data/kingbase/v8r3c/data
# 初始化单实例库
[kingbase@node1 bin]$ ./initdb -U system -W 123456 -E utf8 --case-insensitive -D /data/kingbase/v8r3c/data
The files belonging to this database system will be owned by user "kingbase".
This user must also own the server process.
......
5、拷贝备库数据到单实例库
[kingbase@node1 v8r3c]$ mv data data.bk
[kingbase@node1 v8r3c]$ mkdir data
# 拷贝备库数据到单实例库
[kingbase@node1 data]$ cp -var * /data/kingbase/v8r3c/data/
‘backup_label.old’ -> ‘/data/kingbase/v8r3c/data/backup_label.old’
‘base/1/1255’ -> ‘/data/kingbase/v8r3c/data/base/1/1255’
‘base/1/1255_fsm’ -> ‘/data/kingbase/v8r3c/data/base/1/1255_fsm’
‘base/1/1247’ -> ‘/data/kingbase/v8r3c/data/base/1/1247’
‘base/1/1247_fsm’ -> ‘/data/kingbase/v8r3c/data/base/1/1247_fsm’
.......
6、修改data下的recovery.conf文件[kingbase@node1 data]$ mv recovery.conf recovery.conf.bk
7、启动单实例库数据库服务
[kingbase@node1 bin]$ ./sys_ctl start -D /data/kingbase/v8r3c/data
server starting
[kingbase@node1 bin]$ LOG: redirecting log output to logging collector process
HINT: Future log output will appear in directory "/home/kingbase/cluster/ha/db/data/sys_log".
[kingbase@node1 bin]$ ps -ef |grep kingbase
kingbase 21482 1 1 14:08 pts/1 00:00:00 /home/kingbase/cluster/ha/db/bin/kingbase -D /data/kingbase/v8r3c/data
kingbase 21484 21482 0 14:08 ? 00:00:00 kingbase: logger process
kingbase 21487 21482 0 14:08 ? 00:00:00 kingbase: checkpointer process
kingbase 21488 21482 0 14:08 ? 00:00:00 kingbase: writer process
kingbase 21489 21482 0 14:08 ? 00:00:00 kingbase: wal writer process
kingbase 21490 21482 0 14:08 ? 00:00:00 kingbase: autovacuum launcher process
kingbase 21491 21482 0 14:08 ? 00:00:00 kingbase: archiver process
kingbase 21492 21482 0 14:08 ? 00:00:00 kingbase: stats collector process
kingbase 21493 21482 0 14:08 ? 00:00:00 kingbase: bgworker: syslogical supervisor
......
8、验证和查看单实例库数据
[kingbase@node1 bin]$ ./ksql -U SYSTEM -W 123456 PROD -p 54321
ksql (V008R003C002B0270)
Type "help" for help.
PROD=# \d
List of relations
Schema | Name | Type | Owner
--------+-------------------------------+-------+--------
PUBLIC | PATHMAN_CACHE_STATS | view | SYSTEM
PUBLIC | PATHMAN_CONCURRENT_PART_TASKS | view | SYSTEM
PUBLIC | PATHMAN_CONFIG | table | SYSTEM
PUBLIC | PATHMAN_CONFIG_PARAMS | table | SYSTEM
PUBLIC | PATHMAN_PARTITION_LIST | view | SYSTEM
PUBLIC | T1 | table | SYSTEM
PUBLIC | T2 | table | SYSTEM
PUBLIC | T3 | table | SYSTEM
(8 rows)
PROD=# select count(*) from t1;
COUNT
-------
10000
(1 row)
=== 从以上获知，备库的数据已经同步到单实例库===
总结：
1、本案例是在原集群架构外，另外创建单实例，完成从集群到单实例库的转换，也可以直接在原集群上转换，不再赘述。
2、转换为单实例库后，可以按照生产要求 ，删除或保留原集群架构。
3、另外集群主库转换为单实例库，方法基本和此案例一致。